Central Granular Cell Odontogenic Tumor: Case Report with Literature Review of Cases Reported in the Last 71 years

The central granular cell odontogenic tumor (CGCOT) is a rare, benign, slowly growing, odontogenic neoplasm. CGCOT was not considered as a distinct entity in the WHO classification reported on 2017. This study reports a rare case of CGCOT involving the right side of maxillary anterior region of a 39-year-old white woman. In addition, to better delineate the clinical, radiographic, histopathologic and immunohistochemical characteristics of CGCOT, a literature review of all published cases (in PubMed/ Google Scholar/ MEDLINE/Scopus) of CGCOT is provided. CGCOT is a very uncommon tumor, with only 51 reported cases in the literature. The present case is interesting regarding to its rarity for being in the maxillary anterior region, which has not been previously reported in Asia. The immunohistochemical findings of the current case and other cases in the literature review, verified the mesenchymal origin of granular cells and odontogenic nature of the epithelium islands, which can be a possible promise for placing this lesion in the future WHO odontogenic tumor classification.

Even though WHO proposed the term CGCOT for this lesion [10], there is still a great debate on this nomenclature since it was not considered as a distinct entity in the recent WHO classification [11] of odontogenic tumors. However, recent published studies suggest the term CGCOT for tumors characterized by varying amount of large eosinophilic granular cells with eccentrically placed nuclei associated with apparently inactive odontogenic epithelium [8,[12][13][14][15][16][17][18][19][20][21][22][23][24]. CGCOT is defined as a rare, benign, slow-growing, noninvasive, though nonencapsulated odontogenic neoplasm [25]. This lesion is usually detected in the posterior mandible of women, predominantly in the fifth decade of life [20]. An extraosseous variant [26][27] and a malignant case of central granular cell odontogenic fibroma has also been reported [28].
Herein, we report the new rare case of CGCOT in the anterior area of maxilla in a 39-year-old female.
Subsequently, we provide a literature review of all published cases (51 cases) of CGCOT. The aspiration examination of the lesion was negative. Regarding the clinical, radiological, and aspiration examinations, odontogenic tumors including ameloblastoma and odontogenic myxoma were considered in our differential diagnosis list. Afterwards, an incisional biopsy was performed for histopathological examination.

Case Presentation
Grossly, the specimen was multiple pieces of irregular, gray-brown soft tissue, measuring 1.6×1.3×0.4cm. Incut surface, the lesion was creamy-gray, homogeneous and solid. Microscopic examination of Hematoxylin and Eosin (H&E) stained soft tissue sections discovered a benign mesenchymal odontogenic neoplasm with lobulat   Tables 1-2.
Our review showed that more than half (61%) of patients were older than 40 years of age, which is similarly reported by Sarode et al. [10] and Neville et al. [43].
On IHC examinations, granular cells showed posi- Only one case recurred 13 years after initial treatment [13]. Piattelli et al. [28] in 2003 reported the first and the only case of malignancy in this tumor. However, no case of metastasis has been reported until now.

Conclusion
CGCOT is a rare tumor with only 51 reported cases in the literature. The presented case is rare concerning its location on maxillary anterior region, which has not been yet reported in Asia. IHC findings of the current case and other cases in the present review, confirmed the mesenchymal origin of GCs and odontogenic nature of the epithelium islands, a prominence that necessitates its assignment in the future WHO odontogenic tumor classification.